CVE-2021-33790: Techreborn Reborncore

Critical severity, CVSS 9.8. EPSS: 2.8% chance of exploitation in the next 30 days.

The RebornCore library before 4.7.3 allows remote code execution because it deserializes untrusted data in ObjectInputStream.readObject as part of reborncore.common.network.ExtendedPacketBuffer. An attacker can instantiate any class on the classpath with any data. A class usable for exploitation might or might not be present, depending on what Minecraft modifications are installed.

Affected products

• Techreborn Reborncore: up to and including 3.13.8; from 3.19.0, before 3.19.5 (fixed in 3.19.5); from 4.2.0, before 4.2.10 (fixed in 4.2.10); from 4.7.0, before 4.7.3 (fixed in 4.7.3)

Published 2021-05-31. Last modified 2026-06-17.